Punching apparatus

ABSTRACT

A punching apparatus having a punch holder rigidly supporting two punches which at least partially overlap each other, and dies co-acting with their respective punch, at least one of the dies being movable away from its position in which it cooperates with its respective punch, while said punch objects into a perforation made in a workpiece by the same.

O United States Patent [191 [111 3,777,601 Strandell Dec. 11, 1973 [54] PUNCHING APPARATUS 2,518,433 8/1950 Friedman 83/160 [76] Inventor: Perm Strudel. Bocksfigen 3, 1,428,174 9/1922 Luther 83/621 x Taby, Sweden FORElGN PATENTS OR APPLICATIONS 2 Filed: Mar. 29 1971 3,]85 10/1868 Great Britain.... 83/553 [21] Appl' l28659 Primary Examiner-Andrew R. Juhasz Assistant ExaminerW. D. Bray [52] US. Cl 83/160, 83/562, 83/563, Attorney-Stevens, Davis, Miller & M er 83/621, 83/623, 83/685, 83/688, 83/698 [51] Int. Cl B26d 7/06 57 ABSTRACT [58] Field of Search 83/30, 160, 167,

83/563, 562 553 621 652 682, 684 685, A punching apparatus having a punch holr ler rigidly 701 698 688 supporting two punches WhlCh at least partially overlap each other, and dies co-acting with their respective [56] References Cited punch, at least one of the dies being movable away from its position in which it cooperates with its respec- UNITED STATES PATENTS tive punch, while said punch objects into a perforation 2,41 walpolfi u X made in a workpiece the ame 3,568,554 3/1971 Wiechec 83/621 X 3,227,022 1/1966 Evans et al. 83/623 X 4 Claims, 5 Drawing Figures PATENIH] mac 1 1 I975 SHEEF 2 [IF 4 PATENTEDUEB 1 1 191a 3.771601 sum u BF 4 PUNCHING APPARATUS The present invention relates to an apparatus for punching elements from a flat workpiece, including a punch holder which is capable of moving towards and away from the workpiece and which is rigidly connected to at least two punches, an actuating means for delivering to the punch holder impact forces having sufficient energy to carry out each punching operation, punch dies arranged to co-act with the punches, and means for arresting movement of the punch holder immed'iately after an element has been punched free from the workpiece.

The object of the invention is to provide a novel and. improved punching apparatus of the aforedescribed type which is of simple and inexpensive construction and by means of which elements of a complicated configuration can be punched from a workpiece with precision.

In accordance with the invention, the novel apparatus is characterized in that at least one first punch for making a first perforation in the workpiece is located, when projected onto the workpiece, at least partially within the surface of projection of a second punch for free-punching the elements from the workpiece and extends in the direction of the working stroke of the punch holder beyond the free-punching punch, in that a means is provided for temporarily arresting the movement of the punch holder immediately after the first perforation is made in the workpiece, and in that at least the die associated with the first punch is capable of being moved away from its co-acting position with the first punch means while the first punch projects into a perforation which it has made in the workpiece. As previously mentioned, the precision with which the elements are punched out by means of an apparatus constructed in accordance with the invention is high. Moreover, the problem of removing punched waste material and punched elements can be solved in a very simple manner, and the need of detent means etc., which complicate and increase the price of conventional punching apparatus, is eliminated.

The invention will now be described in more detail with reference to two embodiments thereof illustrated in the accompanying drawing, further features of the invention being discussed in conjunction therewith.

FIG. 1 is a diagrammatic view in vertical section of a first punching apparatus according to the invention.

FIG. 2 is a diagrammatic view in perspective of an apparatus which coincides in all essential details with the apparatus of FIG. 1.

FIG. 3 illustrates diagrammatically an arrangement for automatic operation of the apparatus illustrated in FIGS. 1 or 2.

FIG. 4 is a diagrammatic view in vertical section of a second punching apparatus according to the invention.

FIG. 5 is a diagrammatic view in perspective of an apparatus which coincides in all essential details with the apparatus of FIG. 4.

In FIGS. 13 the reference numeral identifies a table which supports a casing 11 in which a punch holder 12 is mounted for reciprocating movement towards and away from the upper surface of the table 10. The casing 11 is provided at the top thereof with an upper wall portion 13 which, by engagement with a shoulder 14 on the punch holder 12, restricts upward movement of the holder 12. Formed in the wall portion 13 is an opening through which projects a part 15 of the punch holder 12, the part 15 presenting a portion of reduced cross section. Two punches: 16, 17, which are preferably detachable in respect of each other and of the punch holder 12, are rigidly connected to the lower end of the punch holder 12, while the operative portions of the punches 16, 17 of the illustrated example are coaxial with each other and have circular cross sec tion, which are of different diameters for punching ring washer-like elements 18 from a flat workpiece.

The punching apparatus is also provided with a horizontal, through passing passage 20, through which the workpiece can be advanced with the punch means 16, 17 located above the workpiece and either one of two punch dies 21, 22 located beneath the workpiece for cooperation with the punch means. The dies 21, 22 are arranged on a slide 23 which is recip rocatingly movable along the table 10 and actuated by means of a pneumatic pressure cylinder 24 attached to the table. The ends of the slide 23 are provided with abutment surfaces 25 which, by engaging corresponding, suitably adjustable orexchangeable abutment surfaces 26 on the casing 11, are adapted to stop the slide in a position at which the die 21 is located opposite and beneath the punch 16 and the die 22 is located opposite and above a downwardly sloping discharge chute 27 formed in the table 10 for rounds 28 punched from the workpiece by means of punch 17, or in a position where the die 22 is located opposite and beneath the punch 17 and the die 21 is located opposite and above a downwardly sloping discharge chute 29 formed in the table 10 and intended to receive the elements 18. This latter position is indicated by means of broken lines 30 and 31 in FIGS. 1 and 2 respectively.

For the purpose of obtaining clean and true cut surfaces on the rounds 28 and elements 18, the punches 16, 17 are arranged to enter the workpiece a distance which preferably corresponds to only a small part of the thickness of the workpiece, and the punches l6, 17 are stopped immediately after a round 28 or an element 18 has been punched free from the workpiece. Subsequent to free-punching a round 28, the punch 17 is stopped temporarily by engagement between the upper side of the workpiece and the lower surface 32 of the punch 16. For this purpose, the punch 17 is caused to project beyond the punch 16 by an amount which is at least substantially equal to the shortest distance which the punch 17 must enter the workpiece 19 in order to cause a round 28 to be punched free therefrom, while the die 22 in its co-acting position with the punch 17 prevents, by abutment of the workpiece with the surface 32 of the punch 16, an element 18 from being punched free from the .workpiece by means of the punch 16.

As illustrated in FIGS. 1 and 2, when the cross sectional area of the effective portion 33 of the punch 16 intended for free-punching elements 18 is smaller than the punch 16 in general, the punch 16 as the punch 17, can be stopped after free-punching an element 18 by engagement between the upper side of the workpiece and the surface 34 of the punch 16. To this end, the portion 33 is caused to project beyond the punch 16 in general by an amount which is at least substantially equal to the smallest distance which the punch 16 must enter the workpiece 19 in order to free-punch an element 18. The punch 16, however, can also be stopped by engagement between the lower side 35 of the punch holder 12 and an internal shoulder 36 on the casing 11.

Raising of the punch holder 12 subsequent to punch ing out an element 18 is effected by compressed air which is passed by means of a line 37 between the surface 35 and the shoulder 36.

When punching out elements by means of the punching apparatus illustrated in FIGS. 1-3, a workpiece 19 is fed into the passage 20 and the slide 23 is set in a position such that the die 22 is located beneath and in register with the punch means 17. An impact tool 38 (FIG. 3), whose weight is preferably large in relation to the weight of the punch holder 12, is caused to impart to the tool holder 12 sufficient energy to punch out a round 28. The round 28 falls down into the cavity 39 of the die 22 and rests against the upper surface of the table 10. With the punch extending into the perforation thus formed, the slide 23 is moved with the aid of the pressure cylinder 24 to the position in which the die 21 co-acts with the punch 16 and in which the die 22 is located above and in register with the discharge chute 27, so that the round punched from the workpiece passes out through the chute 27 and down into a collecting container (not shown). By then effecting a new working stroke with the tool 38, the punch holder 12 is imparted energy sufficient to free-punch an element 18 from the workpiece 19, the element 18 falling down into a cavity 40 of the die 21 to rest against the upper surface of the table 10. When the energy required to punch a round 28 differs from that required to freepunch an element 18, the requisite energy can be supplied by means of two different impact tools, or alternatively by varying the impact energy of the impact tool, for example by operating the impact tool with a pneumatic piston cylinder assembly 41 (FIG. 3) and by applying a different air pressure in the assembly 41 to punch out a round 28 than that applied to free-punch an element 18. Subsequent to free-punching an element 18, the punch holder 12 is lifted by feeding air through the line 37 until contact is established between the upper wall 13 of the casing 11 and the abutment surface on the punch holder, whereupon the slide 23 is so adjusted that the die 22 is located in register with and beneath the punch 17, the element 18 located in the cavity 40 of the die 21 falling down into the inclined chute 27 and sliding out into a collecting container (not shown). Subsequent to feeding the workpiece 19 a distance in the passage 20 corresponding to the diameter of the element 18, the working cycle described above can be repeated for punching out another element 18.

FIG. 3 illustrates a block diagram of a system for automatically operating in accordance with the above the punching apparatus illustrated in any of FIGS. 1-2 and in FIG. 3. For the purpose of illustrating the mode of operation of the automatic actuation system more clearly, the punching apparatus is illustrated differently to the apparatus of FIGS. 1 and 2. For example, the abutment surfaces 25 of the slide of the apparatus of FIG. 3 are directed downwardly, with the slide reciprocatingly movable in the longitudinal direction of the workpiece 19.

In the embodiment illustrated in FIG. 3, the workpiece 19 is fed towards an arm 42 which transmits a pulse to a valve 43, which thereupon opens to allow air under pressure from a line 44 to pass through said valve. The air under pressure passes, via a line 45, over a switch valve 46 and a line 47 to a diaphragm valve 48 and via a valve body 49 and a line 50 to a valve 51, which opens to communicate with a line 52, which evacuates air from the negative side of the impact cylinder 41. In this way there is obtained a pressure drop in a line 53, whereupon the diaphragm of a diaphragm valve 54 is reversed and the valve is opened to evacuate a valve 55, via a line 56. The valve 55 opens for compressed air L of relatively low pressure arriving from a valve 57 via lines 58, 59 and 60 to the plus side of the impact cylinder 41, and the impact tool 38 makes a stroke with a relatively small amount of energy and punches a round 28 (FIG. 2) from the workpiece. (The slide 23 of the embodiment illustrated in FIG. 3 has al ready been reset to free-punch an element 18).

At the same time, the valve 43 via the line 45 and a line 61, transmits a pulse to a valve 62 which opens a line 63, which evacuates the casing 11 of the punching apparatus of air so that the punch holder 12 falls down against the workpiece 19 before the first punching stroke is effected. When the impact cylinder 41 passes to its lower position, a drop in pressure occurs in lines 64 and 65 leading to the valve 48 and to a diaphragm valve 66 respectively, whereupon the diaphragms of the valves are reversed and the valves reset.

The valve 51 is now evacuated of air via the line 50, the valve 51 being reset by a spring arranged therein. The valve 66 opens to allow compressed air to pass via a line 67 to a valve 68, which allows compressed air to pass through the lines 69, 70 and 71 to the valve 57, which is reset and opens so that compressed air H of relatively high pressure can pass therethrough, and also to a valve 72. The pulse passing through the line 71 resets the valve 72, which passes compressed air to the cylinder 24 via lines 73 and 74, thereby changing the position of the slide 23. When moving, the slide 23 actuates an arm 75 of a valve 76, compressed air being fed from a line 77, via a line 78, to the switch valve 46, which through the line 47 repeats the activation cycle via the diaphragm valve 48, to cause a new stroke to be effected which this time has a higher energy. The punch 16 then punches an element 18 from the workpiece 19. At the same time, the high pressure air passes to a valve 79 via a line 80, which valve then opens to permit compressed air to flow to and through a valve 81, which has been reset by the pressure in the line 67. The valve 43 is actuated and opens to evacuate the valve 62 of air, the valve being reset, whereupon compressed air is then able to lift the punch holder 12. The material feed means indicated by the reference numeral 82 now executes a stroke, whereupon an opening 83 formed in the workpiece 19 by free-punching an element 18 releases the arm 42 of the valve 43 and the process is repeated.

The embodiments of the punching apparatus according to the invention illustrated in FIGS. 4 and 5 coincide in many details with the punching apparatus illustrated in FIGS. 1-3. Thus, there is shown in FIGS. 4 and 5 a table 83 which carries a casing 84 having a punch holder 85 mounted therein for movement in a direction towards and away from the supper surface of the table 83. The casing 84 is provided at the top thereof with an upper wall 86 which, by engagement with an abutment surface 87 on the punch holder 85 restricts movement of the latter in an upward direction. Disposed in the wall 86 is an opening through which protrudes a part 88 of the punch holder 85, the part 88 having a reduced cross section. A punch body, which is preferably detachable in relation to the punch holder, is rigidly connected to the lower end of the punch holder 85, the effective parts 89 and 90 of the punch body in the illustrated example being coaxial with each other and having a circular cross sectional shape but different diameters for punching round details 91 from a flat workpiece 92.

The punching apparatus is provided with a horizontal, through-passing passage (FIG. 5), through which the workpiece 92 can be advanced with the punch parts 89, 90 located above the workpiece, and two dies 93 and 94 cooperating with the punch parts and located beneath the workpiece. The punch die 93 is fixedly connected with a lower portion 95 of the casing 84, while the punch die 94 has a downwardly projecting extension 96 mounted for movement in the portion 95. The punch die 94 is capable of being moved vertically by means of a piston-cylinder assembly 97 attached to the table 83 via a bracket structure, the die 94 moving vertically between a position (FIGS. 4 and 5) determined by abutment surfaces on the casing portion 95 and the extension 96 for cooperation with the punch part 89, and a lower position in which the upper side of the punch die is located immediately beneath an air line 98 for ejecting punched elements 91 through an opening 99 in the casing portion 95 into a collecting container (not shown). The punch holder 85 is stopped when the punch components 89 and 90 have penetrated a predetermined distance into the workpiece 92, in a manner described with reference to the apparatus of FIGS. 1-3, and an air line 100 serves to introduce compressed air for lifting the punch holder until contact is established between the shoulder 87 and the wall 86, in the manner described with reference to FIGS. l-3.

For the purpose of supporting the punch die 94 in its raised position, there is arranged a support wedge 101 which is capable of sliding on the upper surface of the table 83 which is capable of being inserted by means of a piston cylinder 102 mounted on the table 83 into a transversely extending recess in the extension 96, and is withdrawable from the recess to enable the die 94 to be lowered.

Thus, the only difference between the mode of operation of the punching apparatus illustrated in FIGS. 4 and 5 and the mode of operation of the apparatus illustrated in FIGS. l-3 resides in the fact that the punch die 94, subsequent to a round being punched out of the workpiece by means of the punch part 89 and subsequent to withdrawing the support wedge 101, is moved downwardly, while the punch die 93 is constantly located in a position in which it cooperates with the punch part 90. The punch die 94 and its extension 96 are of hollow construction, as illustrated in FIGS. 4 and 5, the rounds punched from the workpiece falling down into the cavity 103, from where they are passed, via a plate 104 and a chute 105, into a collecting container (not shown).

Although the punching apparatus have been described in the aforegoing with reference to the punching of round washers, it will be understood that elements of a different configuration can be punched out to advantage. Thus, it is only necessary that a portion of the forwardly extending punch, when projected onto the workpiece, is located within the projection onto the workpiece of the punch intended for free-punching the elements.

The invention is thus not restricted to the described and illustrated embodiments, but can be modified within the scope of the following claims.

What we claim is:

1. An apparatus for punching elements from a flat workpiece comprising a punch holder capable of moving towards and away from the workpiece and rigidly connected to at least two punches,

actuating means for delivering impact forces to the punch holder with sufficient energy to carry out each punching operation,

punch dies arranged to co-act with the punches,

means for arresting movement of the punch holder immediately after an element has been punched free from the workpiece wherein at least one first punch for making a first perforation in the workpiece is located, when projected onto the workpiece, at least partially within the surface of projection of a second punch for free-punching the elements from the workpiece and projects beyond the free-punching punch through a distance which is substantially equal to the least distance which the first punch must be inserted into the workpiece in order to effect said perforation and further wherein the punch die of the first punch in its coacting position with the first punch prevents by abutment via the workpiece facing the workpiece, free-punching of the elements to be punched out, and means for temporarily arresting the movement of the punch holder immediately after the first perforation is made in the workpiece wherein at least the die associated with the first punch can be moved away from its co-acting position with the first punch while the first punch projects into a perforation which it has made in the workpiece. 3 j

2. An apparatus according to claim 1, characterized in that the punch die intended to co-act with the first punch is capable of being removed in the direction of the working stroke of the punch holder.

3. An apparatus according to claim 1, characterized in that the punch dies are mounted on a punch die holder capable of moving transversely of the working stroke of the punch holder.

4. An apparatus according to claim 1, characterized in that said actuating means are capable of being reset to alternately impart to the punch holder energy adapted for punching said perforation and for freepunching an element. 

1. An apparatus for punching elements from a flat workpiece comprising a punch holder capable of moving towards and away from the workpiece and rigidly connected to at least two punches, actuating means for delivering impact forces to the punch holder with sufficient energy to carry out each punching operation, punch dies arranged to co-act with the punches, means for arresting movement of the punch holder immediately after an element has been punched free from the workpiece wherein at least one first punch for making a first perforation in the workpiece is located, when projected onto the workpiece, at least partially within the surface of projection of a second punch for free-punching the elements from the workpiece and projects beyond the free-punching punch through a distance which is substantially equal to the least distance which the first punch must be inserted into the workpiece in order to effect said perforation and further wherein the punch die of the first punch in its co-acting position with the first punch prevents by abutment via the workpiece facing the workpiece, free-punching of the elements to be punched out, and means for temporarily arresting the movement of the punch holder immediately after the first perforation is made in the workpiece wherein at least the die associated with the first punch can be moved away from its co-acting position with the first punch while the first punch projects into a perforation which it has made in the workpiece.
 2. An apparatus according to claim 1, characterized in that the punch die intended to co-act with the first punch iS capable of being removed in the direction of the working stroke of the punch holder.
 3. An apparatus according to claim 1, characterized in that the punch dies are mounted on a punch die holder capable of moving transversely of the working stroke of the punch holder.
 4. An apparatus according to claim 1, characterized in that said actuating means are capable of being reset to alternately impart to the punch holder energy adapted for punching said perforation and for free-punching an element. 